The advent and continued growth of regional cellular networks has made it much easier to summon help from remote locations on cellular phones. However, it is not always possible to dial a cellular phone for help, be it the local 911 network, police, fire and rescue department, or ambulance service, in the event of an emergency. Moreover, some emergencies, such as assaults or severe injuries, may prevent a victim from providing accurate information relating to the nature of the emergency or the victim's location. For example, a victim may be prevented from speaking because he or she is being restrained by an assailant or because he or she has subsequently lost consciousness as a result of his or her injuries. Indeed, the victim may not even have had a chance to access his or her cellular phone.
While it is possible within a cellular network to determine a location based on the particular cell from which the incoming call is received or by triangulating through several cells, this does not provide reliable position information. The position information that can be obtained in this manner is limited to the cell from which the call originated. Since a cell may encompass a large geographic area, the exact location of a victim may not be readily discernible based only on the cell information. Moreover, locating a victim based on cells presupposes that the victim has had the time and ability to dial the telephone number and press the send button in the first place.
The global positioning system is a network of twenty four satellites which orbit the earth and act as reference points which transmit accurate position information and time signals to a receiver which are the direct measurements of the range to the respective satellites in three dimensions. The signals are processed to resolve the location of the receiver. Cellular telephones have been combined with G.P.S. receivers to provide position information over a cellular connection. Thus, it is possible to determine the location of the cellular user even without the user providing any information other than dialing and sending. However, this again presupposes the user has had the time and the ability to dial the correct number in the first place and then initiate the call by pressing send.
Indeed, where the emergency is an assault, the assailant would likely be privy to the victim's attempt to seek help by activation of the cellular phone just prior to the attack and could simply disable, destroy or discard the cellular telephone. Even if the assailant was not initially privy to the summons for help, the assailant may be alerted to such an attempt by hearing the voice on the other end when responding to the caller.